http://www.nintendonerds.com/categories/wii-u/a-cd-can-be-used-as-a-wii-u-cleaning-disc-r717 Very interesting the drive has the capability to read it. Eventual homebrew use would be good.
It's a nice feature they put in the software, although I think it's specifically designed for those CDs with the brushes on them. Just a little lens cleaning fluid and it knows how to use it rather than listening to that requisite music.
It wont clean the drive though, so its kinda stupid to say it can use it as a cleaning disc. I assume normal cleaning discs are an audio disc (so you can use them in a normal CD player) - so the wii u is basically hard coded that Audio CD = Cleaning Disc. You still need the little bristles to do any cleaning though.